"Reward users interacting with your WordPress website At it’s core, myCRED
allows you to award or deduct points from your users for interacting with
your website like commenting, logging in, publishing content, submitting
forms or attending events. With built-in support for some of the most
popular WordPress plugins out there, myCRED got you covered. You can show
your users their point balance and history via shortcodes or widgets,
giving you the freedom to decide where and what to show your users."
source: http://mycred.me/